TOUGH-SEAL™ 41 is a UL 94 V-0 LISTED, tough and durable fast gelling Potting Compound and Sealant with excellent Thermal Cycling Stability.  

TOUGH-SEAL™ 41 Properties

tough-seal label design
  • UL94 V-0
  • Fast gelling
  • Medium viscosity
  • 200% elongation
  • Shore Hardness: 65A
  • Excellent Thermal Cycling Stability from -40°F (-40°C) to 212°F (100°C)
  • Applications include: automotive LED lighting, automotive sensors and high bay LED lighting

Product Specifications: PC2041AB

TOUGH-SEAL™ 41 is a UL 94 V-0 LISTED, tough and durable fast gelling Potting Compound and Sealant with excellent Thermal Cycling Stability.  This UL APPROVED, medium viscosity material is self-leveling and flows like chocolate syrup around electrical components to ensure complete coverage of your entire PCB or electronic assembly. (UL File#:  QMFZ2.E135297)

TOUGH-SEAL™ 41 has a faster 10-20 minute working time and a Shore Hardness of 65A, which is similar to the hardness of a car tire.  TOUGH-SEAL™ 41 reaches 94% of its full hardness after an overnight cure or with a heat cure of 1 hour at 80°C (176°F). TOUGH-SEAL™ does not exotherm or shrink during curing, therefore there is no embedment stress induced on the electronic components that could cause damage and failure of the PCB or electronic assemblies. Sensitive electronics can be potted safely with low embedment stress TOUGH-SEAL™.

With a high elongation of 200%  when fully cured, TOUGH-SEAL™ 41 maintains exceptional flexibility and thermal cycling stability from –40°C  to 100°C (-40°F to 212°F) without pulling back, wilting, or cracking.  This ensures a tough seal that will stop moisture or other contaminants from damaging sensitive PCB’s and electronics.

TOUGH-SEAL™ has very aggressive adhesion to aluminum, making it a perfect choice for potting aluminum housings in LED lighting applications.  TOUGH-SEAL™ bonds extremely well with most polymers.  For housing and wire insulation materials that are exceptionally difficult to bond to, we offer our KEY PR1200 PRIMER, an aggressive adhesive promoter that is simple to use.

Technical Data Sheet (TDS) & Safety Data Sheet (SDS)

Tough-Seal Series

Physical Properties

Color, Part A


Viscosity at 25°C, cP, Part A, (RVT #5, 20 RPM)


Specific Gravityat 25°C, Part A


Color, Part B


Viscosity at 25°C, cP, Part B, (RVT #5, 20 RPM)


Specific Gravity at 25°C, Part B
1. I 43
Density at 25°C, lbs/gal, Part B
Color, Mix
Viscosity at 25°C, cP, Mix, (RVT #5, 20 RPM)
Specific Gravity at 25°C, Mix
Density at 25°C, lbs/gal, Mix
Mix Ratio by Volume
1A to 2B
Mix Ratio by Weight
55A to 100B
Gel Time at 25°C, Minutes, 100 grams
Shelf Life, Ambient, Part A Bulk (15°C to 35°C)
3 Months
Shelf Life, Ambient, Part B Bulk (15°C to 35°C)
12 Months
Shelf Life, Cold, Part A Bulk (-18°C to 3°C)
12 Months
Shelf Life, Cold, Part B Bulk (-18°C to 3°C)
12 Months
Electrical & Thermal Properties
Dielectric Strength, 25°C, Volts/mil
Volume Resistivity, 25°C, Ohm-cm x (10)12
Dielectric Constant, 25°C – 1 MHz
Dielectric Constant, 25°C – 1 kHz
Dielectric Constant, 25°C – 60 Hz
Dissipation Factor, 25°C – 1 MHz
Dissipation Factor, 25°C – 1 kHz
Dissipation Factor, 25°C – 60 Hz
Heat Capacity Cp, 25°C, J/g°K
Thermal Conductivity, 25°C, W/m°K
Coefficient of Thermal Expansion, ppm/°C
(-) 65°C to 75°C
75°C to 100°C
100°C to 150°C
Coefficient of Thermal Expansion, ppm/°F
(-) 85°F to 167°F
167°F to 212°F
212°F to 302°F
Click to View Chart
Hardness vs Temperature
(-75°C / -103°F)
(-25°C / -13°F)
75 A
5°C / 41°F
66 A
25°C / 77°F
64 A
50°C / 122°F
58 A
66°C / 150°F
54 A
80°C / 176°F
52 A
100°C / 212°F
50 A
120°C / 248°F
150°C / 302°F
Click to View Chart
Hardness vs Ambient Cure Time
1 Hour
10 A
2 Hours
22 A
4 Hours
30 A
8 Hours
33 A
12 Hours
35 A
1 Day
38 A
2 Days
42 A
3 Hours
50 A
4 Hours
55 A
1 Week
60 A
1 Month
65 A
Click to View Chart
Mechanical Properties
Tensile Strength per ASTM D638, 25°C, PSI
Elongation per ASTM D638, Type I, 0.125 in, 25°C
Tensile Lap Shear Strength - per ASTM D1002, 25°C, psi *
Aluminum Bare
90 Co
Steel Bare
85 Ad
Steel Ground
70 Co
Primed Steel
90 Co
Galvanized Steel
80 Co
Tin Plated Steel
90 Co
Chrome Plated Steel
70 Ad
Tensile Lap Shear Strength - per ASTM D3163, 25°C, psi **
FRP – Polyester Fiberglass
50 Ad
Garolite G-9 Melamine/Glass
50 Ad
Garolite G-10 Epoxy/Glass
50 Ad
Garolite XX Phenolic/Paper
45 Ad
Tensile Lap Shear Strength - per ASTM D3163, 25°C, psi **
30 Ad
60 Ad
PVC – Polyvinyl Chloride
50 Ad
CPVC – Chlorinated PVC
50 Ad
ABS – Acylonitrile Butadiene Styrene
45 Ad
PETG – Polyethylene Terephthalate
35 Ad
Lexan – Polycarbonate
45 Ad
Nylon 6/6 – Polyamide
50 Ad
45 Ad
Polyethylene LDPE
65 Ad
Polyethylene HDPE
65 Ad
Teflon PTFE – Polytetrafluoroethylene
50 Ad
Noryl – Polyphenylene Oxide/Polystyrene
60 Ad
Ultem Polyetherimide
50 Ad

Which TOUGH-SEAL™ is Right for you?

TOUGH-SEAL™ is a superior family of KEY sealants available in four standard formulations to fit a variety of potting applications. While all TOUGH-SEAL™ formulations are durable hybrid epoxy elastomers that grip and protect under the most aggressive conditions, they are available in a combination of properties that vary in hardness, gel-time, working time, and flow.

Order Your TOUGH-SEAL™ Evaluation Kit Today!

Your Evaluation Kit will include everything you need to perform your own high quality product evaluation for your application.

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TOUGH-SEAL™ PC is bulldog tough and bred to grip and protect, under the most aggressive conditions.

Contact us for help selecting the correct TOUGH-SEAL™ PC for YOUR application!